Biodegradable base lipid as well as preparation method and application thereof

Abstract

The invention discloses biodegradable base lipid as well as a preparation method and application thereof, the structural formula of the biodegradable base lipid is as shown in formula (I), in the formula (I), a polar head group is a base group and is natural purine or pyrimidine base; n1 is a positive integer selected from 1-10; n2 is a positive integer selected from 1-10; n3 is a positive integer selected from 1-10; x is-O-or-NH-; r1 is a substituted or unsubstituted C6-16 alkyl group, or a substituted or unsubstituted C6-16 alkenyl group, or a substituted or unsubstituted C6-16 alkynyl group, or a substituted or unsubstituted C6-16 alkynyl group; and R2 is a substituted or unsubstituted C6-16 alkyl group, a substituted or unsubstituted C6-16 alkenyl group, or a substituted or unsubstituted C6-16 alkynyl group. An ester bond structure is introduced to the hydrophobic tail part of the lipid, so that the biodegradability of the lipid compound is remarkably enhanced, and meanwhile, the efficient nucleic acid delivery capability of the lipid compound is reserved.

Description

Technical Field

[0001] The present invention belongs to the field of biomedicine technology, and specifically relates to a biodegradable basic lipid and a preparation method and application thereof. Background Art

[0002] The statements herein merely provide background information related to the present invention and do not necessarily constitute prior art.

[0003] Gene therapy aims to treat diseases by delivering exogenous genetic material to target cells. Its application has significantly expanded beyond traditional single-gene genetic diseases to encompass major health challenges such as cancer, infectious diseases, and cardiovascular disease. However, nucleic acid-based drugs face two major challenges in their clinical application: first, nucleic acid molecules are easily rapidly degraded by nucleases, which are widely present in the body, and lose their activity; second, their large molecular weight and strong negative charge significantly hinder their effective cellular uptake.

[0004] Among existing delivery vectors, viral vectors exhibit high transfection efficiency, but their potential immunogenicity and potential safety concerns of inducing insertional mutagenesis cannot be ignored. In contrast, non-viral vectors (such as ionizable lipid nanoparticles) have become a hot topic of research due to their advantages such as precise structural design and relatively good safety.

[0005] This type of ionizable liposome can be protonated in an acidic environment, binding nucleic acids and protecting them from degradation through electrostatic interactions, but it returns to electrical neutrality under physiological pH conditions, thereby reducing its cytotoxicity. However, the types of ionizable lipids currently available for commercial use are relatively limited, and there is an urgent need to achieve a better balance between transfection efficiency and biosafety. It is particularly noteworthy that traditional liposomes lack specific interactions with nucleic acids, and relying solely on relatively weak electrostatic binding may lead to insufficient carrier stability. In addition, existing lipid synthesis methods are usually cumbersome and costly, which constitutes an important bottleneck for the widespread clinical transformation of nucleic acid drugs. Summary of the Invention

[0006] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a biodegradable base lipid and its preparation method and application. The present invention significantly enhances the biodegradability of lipid compounds by introducing an ester bond structure into the hydrophobic tail of the lipid, while retaining its efficient nucleic acid delivery ability. The preparation method is simple, the raw materials are cheap and easy to obtain, the reaction conditions are mild, and the product can be separated in high yield by conventional extraction and column chromatography. The prepared ester bond modified lipid can be protonated under acidic conditions, stably binds to nucleic acid drugs through electrostatic interaction, and the ester bond structure is easily hydrolyzed and metabolized by esterase in the body, with both high transfection efficiency and low cytotoxicity.

[0007] In order to achieve the above object, the present invention is implemented through the following technical solutions: In a first aspect, the present invention provides a biodegradable basic lipid, the structural formula of which is shown in formula (I):

[0008] (Ⅰ) Wherein, the polar head group is a base group, which is a natural purine or pyrimidine base; n1 is a positive integer selected from 1 to 10; n2 is a positive integer selected from 1 to 10; n3 is a positive integer selected from 1 to 10; X is -O- or -NH-; R1 is substituted or unsubstituted C 6-16 Alkyl, substituted or unsubstituted C 6-16 Alkenyl, substituted or unsubstituted C 6-16 Alkynyl; R2 is substituted or unsubstituted C 6-16 Alkyl, substituted or unsubstituted C 6-16 Alkenyl, substituted or unsubstituted C 6-16 Alkynyl.

[0009] In some embodiments, the purine group is adenine (A) or guanine (G); the pyrimidine group is cytosine (C), thymine (T) or uracil (U).

[0010] In some embodiments, the biodegradable basic lipid is selected from one of the following compounds: ; ; ; .

[0011] In a second aspect, the present invention provides a method for preparing the biodegradable basic lipid, comprising the following steps: ; , X' is an amino group or a hydroxyl group; The compound represented by formula (II) and the compound represented by formula (III) are subjected to catalytic reaction in an organic solvent in proportion to obtain the product.

[0012] In some embodiments, the molar ratio of the compound represented by (II) to the compound represented by (III) is 1:0.8-1.5.

[0013] In some embodiments, the organic solvent is at least one of methanol, ethanol, isopropanol, benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, cyclohexanone, toluene cyclohexanone, chlorobenzene, dichlorobenzene, dichloromethane, ethyl ether, propylene oxide, acetone, methyl butyl ketone, methyl isobutyl ketone, acetonitrile, pyridine, phenol, styrene, perchloroethylene, trichloroethylene, ethylene glycol ether and triethanolamine.

[0014] In some embodiments, the catalyst for the catalytic reaction is at least one of N-hydroxysuccinimide (NHS), dicyclohexylcarbodiimide (DCC), diisopropylcarbodiimide (DIC), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI), 1-hydroxybenzotriazole (HOBT), O-benzotriazole-tetramethyluronium hexafluorophosphate (HBTU) or O-benzotriazole-N,N,N',N'-tetramethyluronium tetrafluoroborate (TBTU).

[0015] In some embodiments, the catalytic reaction temperature is 35-40°C, and the reaction time is 10-20 hours; preferably, the catalytic reaction temperature is 37°C.

[0016] In a third aspect, the present invention provides use of the biodegradable basic lipid in preparing a drug delivery carrier.

[0017] In some embodiments, the drug delivery vehicle is a lipid nanoparticle.

[0018] Preferably, the lipid nanoparticles are composed of the biodegradable base lipid, auxiliary lipid, cholesterol, PEG lipid and drug, the molar fraction of the biodegradable base lipid is 10%~50%, the molar fraction of the auxiliary lipid is 10%~40%, the molar fraction of cholesterol is 30%~60%, the molar fraction of PEG lipid is 0.5%~10%, and the mass ratio of drug to biodegradable base lipid is 1:8-15.

[0019] Further preferably, the helper lipid is selected from at least one of distearoylphosphatidylcholine (DSPC), dioleoylphosphatidylethanolamine (DOPE), dipalmitoylphosphatidylcholine (DPPC), diethyl pyrocarbonate (DEPC), phosphatidylcholine (POPC) and dimyristoylphosphatidylcholine (DMPC).

[0020] More preferably, the helper lipid is DOPE.

[0021] Further preferably, the PEG lipid is selected from at least one of dipalmitoylphosphatidylethanolamine-polyethylene glycol (DPPE-PEG), dimethacrylate-polyethylene glycol (DMA-PEG), distearoylphosphatidylethanolamine-polyethylene glycol (DSPE-PEG) or dimyristylglycerol-polyethylene glycol (DMG-PEG).

[0022] More preferably, the helper lipid is DMG-PEG.

[0023] Preferably, the diameter of the lipid nanoparticles is 10 -3 For example, the particle diameter is 1-100 μm, or 1-10 μm, or 10-100 μm, or in the range of 20-800 nm, or 50-500 nm, or 80-200 nm, or 1-10 nm.

[0024] Methods for preparing lipid nanoparticles include, but are not limited to, liposome extrusion, thin film hydration, nanoprecipitation, microfluidics, and impinging jet mixing, as well as other methods known to those skilled in the art.

[0025] Further preferably, the drug is a biological drug or a chemical drug; the biological drug is selected from at least one of nucleic acid, protein, polypeptide or polysaccharide; the chemical drug is a small molecule drug, fluorescein or developer.

[0026] More preferably, the nucleic acid is selected from at least one of small interfering RNA (siRNA), messenger RNA (mRNA), microRNA (miRNA), circular mRNA, long non-coding RNA (lncRNA), plasmid DNA (pDNA), mini circle DNA (mcDNA), antisense oligonucleotides (ASOs), small activating RNA (saRNA) and aptamers.

[0027] More preferably, the drug is pDNA, and the mass ratio of the biodegradable base lipid to pDNA is 1-100:1.

[0028] Preferably, the drug delivery vector is modified with a targeting molecule, wherein the targeting molecule is selected from at least one of proteins, peptides, glycoproteins, lipids, small molecules, or nucleic acids, including (but not limited to) antibodies, antibody fragments, low-density lipoprotein (LDL), transferrin, asialoglycoprotein, receptor ligands, sialic acid, aptamers, and the like.

[0029] The nanopharmaceutical preparations of the present invention can be administered to humans and / or animals orally, rectally, intravenously, intramuscularly, vaginally, intranasally, intradermally, intraperitoneally, buccally, or in the form of an oral or nasal spray. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0031] Figure 1 This is the synthetic route for the base ionizable lipids of Examples 5-8 of the present invention.

[0032] Figure 2 is the encapsulation efficiency of the lipid nanoparticles in Example 9 of the present invention.

[0033] Figure 3 It is the particle size and zeta potential characterization of the lipid nanoparticles in Example 9 of the present invention.

[0034] Figure 4 This is the transmission electron microscopy characterization of the lipid nanoparticles in Example 9 of the present invention.

[0035] Figure 5 This is an evaluation of the in vivo tumor cell transfection efficiency of lipid nanoparticles in Experimental Example 1 of the present invention.

[0036] Figure 6 This is a graph showing the results of in vitro toxicity investigation of different lipid nanoparticles on MLE-12 cells in Experimental Example 2 of the present invention.

[0037] Figure 7 This is a graph showing the results of in vitro toxicity investigation of different lipid nanoparticles on RAW 264.7 cells in Experimental Example 2 of the present invention. DETAILED DESCRIPTION

[0038] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0039] Explanation of terms: "Alkyl" refers to a saturated aliphatic hydrocarbon group, including straight-chain and branched-chain alkyl groups. In some embodiments, the alkyl group has 6-16 carbon atoms, also known as C 6-16 Alkyl. The alkyl group may be unsubstituted or substituted with one or more groups selected from halogen, hydroxy, amino, oxo, alkoxycarbonyl, amido, alkylamido, dialkylamido, nitro, amino, alkylamino, dialkylamino, carboxyl, thio, and thioalkyl.

[0040] "Alkenyl" refers to an unsaturated aliphatic hydrocarbon group, including straight-chain and branched alkenyl groups. In some embodiments, the alkenyl group has 6-16 carbon atoms, also known as C 6-16 Alkenyl. Alkenyl includes, for example, ethenyl, propenyl, n-butenyl, isobutenyl, and the like. Alkenyl groups may be unsubstituted or substituted with one or more groups selected from halogen, hydroxy, amino, oxo, alkoxycarbonyl, acylamino, alkylacylamino, dialkylacylamino, nitro, amino, alkylamino, dialkylamino, carboxyl, thio, and thioalkyl groups.

[0041] "Alkynyl" refers to an unsaturated aliphatic hydrocarbon group, including straight and branched alkynyl groups. In some embodiments, the alkynyl group has 6-16 carbons and is also referred to as a C6-16 alkynyl. Alkynyl includes, for example, ethynyl, 2-propynyl (propargyl), 1-propynyl, etc. The alkynyl group can be unsubstituted or substituted by one or more groups selected from halogen, hydroxyl, amino, oxo, alkoxycarbonyl, acylamino, alkylacylamino, dialkylacylamino, nitro, amino, alkylamino, dialkylamino, carboxyl, thio and thioalkyl.

[0042] "Substitution" refers to that one or more hydrogen atoms in a group are independently replaced by a corresponding number of substituents. It goes without saying that substituents are only in their possible chemical positions, and those skilled in the art can determine (by experiment or theory) possible replacements without paying too much effort.

[0043] The present disclosure is further described below with reference to examples, but these examples are not intended to limit the scope of the present disclosure.

[0044] Experimental methods in the examples of this disclosure that do not specify specific conditions are generally based on conventional conditions or the conditions recommended by the raw material or product manufacturers. Reagents without specific sources are conventional reagents purchased from the market.

[0045] Example 1 Synthesis of intermediate 1a, behenyl 3,3'-(2-((tert-butoxycarbonyl)amino)ethyl)azepinediyl)dipropionate.

[0046] Accurately weigh N-Boc-ethylenediamine (801.1 g, 5 mmol) into a round-bottom flask and dissolve it in acetonitrile. Add lauryl acrylate (3.605 g, 15 mmol) and an appropriate amount of triethylamine. The reaction mixture was refluxed in an oil bath at 90°C for 12 h. The reaction mixture was concentrated under reduced pressure, and the residue was purified by silica gel column chromatography (200-300 mesh silica gel; eluent: ethyl acetate / petroleum ether 0-10%) to obtain intermediate 1a in a 43% yield.

[0047] Example 2 The synthesis of intermediate 2a, i.e., behenyl 3,3'-((2-((tert-butoxycarbonyl)amino)ethyl)azepinediyl)dipropionate, was as described in Example 1, except that dodecyl acrylate was replaced by tetradecyl acrylate; the other steps and conditions were the same as in Example 1.

[0048] Example 3 Synthesis of intermediate 1b, docosyl 3,3'-((2-aminoethyl)azinediyl)dipropionate.

[0049] Intermediate 1a (705.1 mg, 1.1 mmol) was accurately weighed into a round-bottom flask and dissolved in dichloromethane. Trifluoroacetic acid was added dropwise and stirred for 6 h. The reaction solution was dried under reduced pressure to remove the solvent. Saturated brine was added to the residue, and the mixture was extracted with ethyl acetate. The organic phase was washed three times with saturated NaCl solution. Residual water was removed from the organic solvent, and the mixture was filtered. The solvent was then removed by rotary evaporation to obtain intermediate 1b in a 96% yield.

[0050] Example 4 The synthesis of intermediate 2b, ie, tricosyl 3,3'-((2-aminoethyl) azodiyl) dipropionate, was as described in Example 3, except that intermediate 1a was replaced by intermediate 2a; the other steps and conditions were the same as in Example 1.

[0051] Example 5 Synthesis of Compound 1, ie, docosyl 3,3'-((2-(2-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamido)ethyl)azinediyl)dipropionate.

[0052] Accurately weigh thymine-1-acetic acid (169.1 mg, 1 mmol), EDCI (210.9 mg, 1 mmol), and NHS (126.6 mg, 1 mmol), dissolve in DMF, and stir at room temperature for 1 h. Add intermediate 1b (595.0 mg, 1 mmol) under ice-cooling and stir at room temperature for 12 h. Add saturated brine to the reaction mixture, and extract with an appropriate amount of ethyl acetate. Remove any residual water from the organic phase, filter, and concentrate the reaction solution by rotary evaporation. The residue is purified by silica gel column chromatography (200-300 mesh silica gel; eluent: methanol / dichloromethane 0-10%) to obtain compound 1 in a 52% yield. The product's NMR data are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.70 (s, 1H), 7.19 (d, J = 5.4 Hz, 1H), 7.10 (s, 1H), 4.42 (s, 2H), 4.07 (t, J = 6.7 Hz, 4H), 3.37 (q, J = 5.3 Hz, 2H), 2.76 (t, J = 6.4 Hz, 4H), 2.57(t, J = 5.3 Hz, 2H), 2.43 (t, J = 6.4 Hz, 4H), 1.93 (s, 3H), 1.64 (p, J = 6.8 Hz,4H), 1.27 (s, 36H), 0.89 (t, J = 6.6 Hz, 6H).

[0053] Example 6 The synthesis of compound 2, i.e., tricosyl 3,3'-((2-(2-(5-methyl-2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamido)ethyl)nitrogendiyl)dipropionate, is as shown in Example 5, except that intermediate 1b is replaced by intermediate 2b; the other steps and conditions are the same as in Example 5. Compound 2 was obtained with a yield of 29%. The NMR data of the product are as follows: 1H NMR (400 MHz, CDCl3) δ 8.38 (s, 1H), 7.11 (t, J = 5.1 Hz, 1H), 7.02(s, 1H), 4.34 (s, 2H), 3.99 (t, J = 6.8 Hz, 4H), 3.29 (q, J = 5.3 Hz, 2H),2.67 (t, J = 6.5 Hz, 4H), 2.49 (t, J = 5.4 Hz, 2H), 2.35 (t, J = 6.4 Hz, 4H),1.85 (s, 3H), 1.56 (p, J = 6.8 Hz, 4H), 1.19 (s, 44H), 0.81 (t, J = 6.7 Hz,6H). Example 7 The synthesis of compound 3, i.e., 3,3'-((2-(2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamido)ethyl)azodiyl)dipropionate, was as shown in Example 5, except that thymine-1-acetic acid was replaced with 2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetic acid; the other steps and conditions were the same as in Example 5. Compound 3 was obtained with a yield of 37%. The NMR data of the product are as follows: 1 H NMR (400 MHz, CDCl3) δ 8.10 (s, 1H),7.15 (s, 1H), 4.52 (d, J = 99.0 Hz, 2H), 4.02 (t, J = 6.8 Hz, 2H), 3.32 (d, J = 5.7Hz, 1H), 2.69 (t, J = 6.5 Hz, 2H), 2.37 (t, J = 6.3 Hz, 2H), 1.21 (s, 30H), 0.83(q, J = 6.9 Hz, 6H). Example 8 The synthesis of compound 4, i.e., 3,3'-((2-(2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetamido)ethyl)azodiyl)dipropionate, was as shown in Example 5, except that thymine-1-acetic acid was replaced with 2-(2,4-dioxo-3,4-dihydropyrimidin-1(2H)-yl)acetic acid, and intermediate 1b was replaced with intermediate 2b; the other steps and conditions were the same as in Example 5. Compound 4 was obtained with a yield of 22%, and the NMR data of the product are as follows: 1 H NMR (400MHz, CDCl3) δ 8.29 (s, 1H), 5.64 (d, J = 7.9 Hz, 1H), 4.37 (s, 1H), 3.99 (t, J =6.8 Hz, 2H), 3.30 (q, J = 5.3 Hz, 2H), 2.67 (t, J = 6.4 Hz, 2H), 2.49 (t, J = 5.4Hz, 2H), 2.35 (t, J = 6.3 Hz, 2H), 2.21 (dt, J = 42.4, 7.6 Hz, 2H), 1.94 (d, J =5.9 Hz, 2H), 1.56 (p, J = 7.0 Hz, 4H), 1.36 (s, 1H), 1.19 (s, 40H), 0.81 (t, J =6.6 Hz, 6H). Example 9 Preparation and characterization of lipid nanoparticles The base ionizable lipid prepared in Example 5, cholesterol, DMG-PEG, and DOPE were dissolved in ethanol at a molar ratio of 33:44:1:22 to prepare a lipid ethanol solution (wherein the base ionizable lipid concentration was 10 mg / mL). pDNA was dissolved in a potassium hydrogen phthalate-sodium hydroxide buffer at pH 4 to prepare a pDNA solution. Using a NanoAssemblr microfluidic device (Precision Nanosystems), the lipid ethanol solution and the pDNA solution were rapidly mixed at a base ionizable lipid:pDNA weight ratio of 10:1 to prepare a solution containing lipid nanoparticles.

[0054] The encapsulation efficiency was determined using the Quant-iT Pico-Green dsDNA quantification kit. Figure 2As shown in the figure, the encapsulation efficiency is 90.70%, and the lipid nanoparticles composed of base ionizable lipids can effectively encapsulate pDNA.

[0055] After the solution containing lipid nanoparticles was dialyzed to remove ethanol, the lipid nanoparticles were characterized using dynamic light scattering and transmission electron microscopy. Figure 3 , Figure 4 As shown, the lipid nanoparticles are uniformly dispersed spherical structures with a particle size of about 140 nm and a surface charge close to neutrality.

[0056] Test Example 1 Performance test of lipid nanoparticles delivering pDNA in vivo Preparation of lipid nanoparticles: The base-ionizable lipid (Compound 1) prepared in Example 5, cholesterol, DMG-PEG, and DOPE were dissolved in ethanol at a molar ratio of 33:44:1:22 to prepare a lipid-ethanol solution (wherein the molar concentration of the base-ionizable lipid was 10 mg / mL). Green fluorescent protein (GFP) pDNA was dissolved in a potassium hydrogen phthalate-sodium hydroxide buffer at pH 4 to prepare a pDNA solution. Using a NanoAssemblr microfluidic device (Precision NanoSystems), the lipid-ethanol solution and the pDNA solution were rapidly mixed at a base-ionizable lipid:pDNA weight ratio of 10:1 to prepare a lipid nanoparticle-containing solution. The lipid nanoparticle-containing solution was dialyzed to remove the ethanol, yielding lipid nanoparticles (LNP-pDNA).

[0057] Evaluation of the in vivo tumor cell transfection efficiency of lipid nanoparticles in a brain tumor mouse model: Luci + GL261 cells were cultured at 37°C and 5% CO2. Cells in the logarithmic phase were digested and resuspended in PBS and counted. The cell suspension concentration was adjusted to 1.5 × 10 7 Cells / mL were placed on ice until ready for use. Mice were anesthetized using a mixture of isoflurane and oxygen and fixed in a stereotaxic apparatus. After disinfection, the skin was cut open along the midline of the mouse's head to fully expose the skull. A hole was then drilled 0.6 mm below and 1.8 mm to the right of the bregma. A microinjection needle was used to slowly inject 10 μL of the tumor cell suspension into the mouse brain. The solution was retained for 2 minutes until the cells were completely absorbed, and then the needle was slowly withdrawn. Finally, the needle hole in the mouse skull was sealed with bone wax, the skin was sutured, and the mouse was kept warm until it regained consciousness.

[0058] After 12 days of tumor growth, mice were randomly divided into groups and injected intratumorally with Free pDNA or LNP-pDNA. The group injected with an equal volume of PBS served as a control. 48 hours after administration, mice in each group were euthanized, and brain tumor tissues were isolated and cut into 1 mm3 Prepare single cell suspension from tissue blocks of about 1000 rpm, centrifuge at 1000 rpm for 5 min, discard the supernatant, add appropriate amount of red blood cell lysis buffer to resuspend the cells, incubate at room temperature for 5 min, add excess PBS to terminate lysis, centrifuge (1000 rpm, 5 min) to collect cells, and detect the proportion of cells expressing GFP by flow cytometry. The results are as follows Figure 5 As shown, the transfection efficiency of LNP-pDNA was 39.47%.

[0059] Test Example 2 Evaluation of the cytotoxicity of lipid nanoparticles in vitro MLE-12 cells and RAW 264.7 cells in the logarithmic growth phase were cultured at 5×10 3 / well were seeded on a 96-well plate and incubated overnight in a 37°C incubator. Subsequently, LNPs prepared from the commercial lipid Dlin-MC3-DMA, LNPs prepared based on different base ionizable lipids (Compound 1, Compound 2, Compound 3 and Compound 4) (LNP1, LNP2, LNP3, LNP4) and an equal volume of PBS (Control group) were co-incubated with MLE-12 cells and RAW 264.7 cells, respectively. After the incubation, the cell activity was detected by CCK-8 kit. Figure 6 、 7 The results show that after administration, the LNPs prepared based on the four different base ionizable lipids of the present invention had no significant effect on the viability of the above two representative cells, and the cytotoxicity was negligible. In addition, the cytotoxicity of the LNPs prepared based on the four different base ionizable lipids of the present invention was lower than that of the LNPs prepared by Dlin-MC3-DMA, indicating that the LNPs provided by the present invention have excellent biocompatibility and good biodegradability.

[0060] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A biodegradable basic lipid, characterized in that: Its structural formula is shown in formula (I): (Ⅰ) Wherein, the polar head group is a base group, which is a natural purine or pyrimidine base; n1 is a positive integer selected from 1 to 10; n2 is a positive integer selected from 1 to 10; n3 is a positive integer selected from 1 to 10; X is -O- or -NH-; R1 is substituted or unsubstituted C 6-16 Alkyl, substituted or unsubstituted C 6-16 Alkenyl, substituted or unsubstituted C 6-16 Alkynyl; R2 is substituted or unsubstituted C 6-16 Alkyl, substituted or unsubstituted C 6-16 Alkenyl, substituted or unsubstituted C 6-16 Alkynyl.

2. The biodegradable basic lipid according to claim 1, wherein: The purine group is adenine or guanine; the pyrimidine group is cytosine, thymine or uracil.

3. The biodegradable basic lipid according to claim 1, wherein: The biodegradable basic lipid is selected from one of the following compounds: ； ； ； 。 4. The method for preparing the biodegradable basic lipid according to any one of claims 1 to 3, characterized in that: The steps include: ; , X' is an amino group or a hydroxyl group; The compound represented by formula (II) and the compound represented by formula (III) are subjected to catalytic reaction in an organic solvent in proportion to obtain the product.

5. The method for preparing the biodegradable basic lipid according to claim 4, wherein: The organic solvent is at least one of methanol, ethanol, isopropanol, benzene, toluene, xylene, pentane, hexane, octane, cyclohexane, cyclohexanone, toluene-cyclohexanone, chlorobenzene, dichlorobenzene, dichloromethane, ethyl ether, propylene oxide, acetone, methyl butyl ketone, methyl isobutyl ketone, acetonitrile, pyridine, phenol, styrene, perchloroethylene, trichloroethylene, ethylene glycol ether and triethanolamine; Alternatively, the catalyst for the catalytic reaction is at least one of N-hydroxysuccinimide, dicyclohexylcarbodiimide, diisopropylcarbodiimide, 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, 1-hydroxybenzotriazole, O-benzotriazole-tetramethyluronium hexafluorophosphate, or O-benzotriazole-N,N,N',N'-tetramethyluronium tetrafluoroborate; Alternatively, the catalytic reaction temperature is 35-40° C. and the reaction time is 10-20 h.

6. Use of the biodegradable basic lipid according to any one of claims 1 to 3 in the preparation of a drug delivery carrier.

7. The use according to claim 6, characterized in that: The drug delivery carrier is a lipid nanoparticle; Preferably, the lipid nanoparticles are composed of the biodegradable base lipid, helper lipid, cholesterol, PEG lipid and drug, the molar fraction of the biodegradable base lipid is 10% to 50%, the molar fraction of the helper lipid is 10% to 40%, the molar fraction of cholesterol is 30% to 60%, the molar fraction of the PEG lipid is 0.5% to 10%, and the mass ratio of the drug to the biodegradable base lipid is 1:8-15; Preferably, the helper lipid is selected from at least one of distearoylphosphatidylcholine, dioleoylphosphatidylethanolamine, dipalmitoylphosphatidylcholine, diethyl pyrocarbonate, phosphatidylcholine and dimyristoylphosphatidylcholine; More preferably, the helper lipid is DOPE; Further preferably, the PEG lipid is selected from at least one of DSPE-PEG, DMG-PEG, DPPE-PEG and DMA-PEG; More preferably, the helper lipid is DMG-PEG.

8. The use according to claim 6, characterized in that: The diameter of the lipid nanoparticles is 10 -3 For example, the particle diameter is 1-100 μm, or 1-10 μm, or 10-100 μm, or in the range of 20-800 nm, or 50-500 nm, or 80-200 nm, or 1-10 nm.

9. The use according to claim 6, characterized in that: The drug is a biological drug or a chemical drug; the biological drug is selected from at least one of nucleic acid, protein, polypeptide or polysaccharide; the chemical drug is a small molecule drug, fluorescein or developer; Preferably, the nucleic acid is selected from at least one of siRNA, mRNA, miRNA, circular mRNA, lncRNA, plasmid DNA, mcDNA, ASOs, saRNA and Aptamer; Preferably, the drug is pDNA, and the mass ratio of the biodegradable base lipid to pDNA is 1 to 100:

1.

10. The use according to claim 6, characterized in that: The drug delivery carrier is modified with a targeting molecule, and the targeting molecule is selected from at least one of proteins, peptides, glycoproteins, lipids, small molecules or nucleic acids.

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